CHARACTERIZATION OF MECP2, A VERTEBRATE DNA-BINDING PROTEIN WITH AFFINITY FOR METHYLATED DNA
CHARACTERIZATION OF MECP2, A VERTEBRATE DNA-BINDING PROTEIN WITH AFFINITY FOR METHYLATED DNA
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DOI：
10.1093/nar/20.19.5085
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发表时间：
1992-10-11
影响因子：
14.9
通讯作者：
BIRD, AP
中科院分区：
文献类型：
--
作者：
MEEHAN, RR;LEWIS, JD;BIRD, AP
脊椎动物中的甲基化 DNA 与转录抑制和染色质失活有关。已鉴定出两种活性：MeCP1 和 MeCP2，它们与含有甲基 CpG 对的 DNA 特异性结合。在本报告中，我们描述了 MeCP2 的特征。我们证明它比 MeCP1 更丰富，在细胞核中结合更紧密，并且可以通过色谱法区分。这两种蛋白在哺乳动物体细胞中广泛表达，而在早期胚胎细胞中几乎检测不到表达。含有第 5 位具有甲基的胸苷的 DNA 不是 MeCP 的配体。在体外转录提取物中测试了 MeCP2 在甲基化相关基因失活中的可能作用。纯化的 MeCP2 在体外抑制甲基化和非甲基化 DNA 模板的转录，这可能是由于蛋白质内存在非特异性 DNA 结合域。我们假设 MeCP2 通常在染色质环境中结合甲基化 DNA，有助于甲基 CpG 的长期抑制和核酸酶抗性。
Methylated DNA in vertebrates is associated with transcriptional repression and inactive chromatin. Two activities have been identified, MeCP1 and MeCP2, which bind specifically to DNA containing methyl-CpG pairs. In this report we characterize MeCP2. We show that it is more abundant than MeCP1, is more tightly bound in the nucleus, and is distinguishable chromatographically. The two proteins share widespread expression in somatic mammalian cells, and barely detectable expression in early embryonic cells. DNAs containing thymidine which has a methyl group at position 5 are not ligands for the MeCPs. The possible role of MeCP2 in methylation-associated gene inactivation was tested in in vitro transcription extracts. Purified MeCP2 inhibited transcription from both methylated and nonmethylated DNA templates in vitro, probably due to the presence of nonspecific DNA binding domains within the protein. We hypothesise that MeCP2 normally binds methylated DNA in the context of chromatin, contributing to the long-term repression and nuclease-resistance of methyl-CpGs.